The strongest magnets you might find are those removed from old PATA hard disk computer drives. Possibly dead SATA drives, however by the time the SATA scheme took hold it was discovered weaker magnets would suffice.
If this speedometer project goes toes up on you (which I don't think it will) and if you are going to be swapping rear end and transmission anyhow, I am considering making a "look-alike" GPS speedometer (my plan is to make one which will simply bolt in to the stock housing and use a new-style face plate either with or without turn signal indicators). You can see what mine looks like below. It isn't exact, but it is as close as anything I've seen. It uses the old style bulbs (plus an led for high beam) so it will not look different at night. One slight drawback is making the face plate. I will have to enlist some help in writing the CNC program since it will need to use X-Y-Z and not just X-Y (which I can handle).
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
